# Python matplotlib MathText with variables

I need to document calculations including

1. the used equation and
2. the variables replaced by the values used

Example: A=1, B=2

C=A+B

3=1+2

I am using Reportlab and create flowable elements with matplotlib. The following code based on the help and can achieve No.1 from the list above. Two questions arise:

1. How can I insert variable values in my `mathtext_demo`?

2. Is there a way to write the general equation and the one with substituted values and result using some dictionary/solv

```import matplotlib.pylab as plt

mathext_demos = (r'\$(frac{5 - frac{1}{x}}{4})\$')

def make_equation(code,fsize=20,imgheight=70):
fig=plt.figure(figsize=(7, 0.1))

plt.annotate(code,
xy=(.4, 0.1), ha='center', fontsize=fsize)
plt.axis('off')

make_equation(mathext_demos)
```

1. You can use variables in your string:
```a = 5
b = 4
mathext_demos = (r'\$(frac{%s - frac{1}{x}}{%s})\$' %(str(a), str(b)))
```

You can also use `%f` for float, but I think that is something you have to figure out what works for you.

1. You can write a function with the arguments `a` and `b` for example en return the string. Is that what you meant with your second question?
```def create_mathtext(a,b):
c = a + b
return r'\${%s} = {%s} + {%s}\$' % tuple(map(str, [c, a, b]))

make_equation( create_mathtext(1, 2))
```